i would check any 2 minute blackhorn fights for invalid reports, they all seem fishy and unless adds instantly die its basically impossible.88mil hp between goriona and blackhorn, 60mil hp for all the melee adds, about 20mil for the drakes. 6mil for the sapper. about 20mil of goriona's hp is taken off by the cannon, so assume their total hp is 68mil now. cannon did about 4mil, so we can shave 5 mil off the drake, so like 16mil. basically you have about 150mil damage to deal.top ultraxion heroic kills still take 5.5-6 minutes to burn 276mil. assuming the top guilds were the ones to do normal mode blackhorn, it would still take them atleast 3 minutes.

that being said i am pretty sure you can put a thing in to not count fights under 3 minutes.(also on lfr we killed everything too fast, so we had to wait like 10-20 seconds for new adds. now on regular this has not happened to me because we are bad dps, but i would assume it does still have a timer that does not shorten if you kill adds too quickly)